The present invention generally relates to the field of reentry vehicles, and more particularly to an integrated sample return capsule for use in returning core samples and the like to Earth.
An objective of sample return missions, such as the Mars Sample Return (MSR) mission, is to retrieve core samples and the like from other celestial bodies (e.g., Mars) and return the samples to Earth for analysis. A critical requirement of sample return missions is sample containment throughout Earth reentry. Due to the possibility of unknown hazards, it may be required that all samples be sufficiently contained and treated as potentially hazardous until proven otherwise, and unless sample containment can be verified en-route to Earth, samples may need to be sterilized in space or not returned. As may be appreciated, sterilization of samples in space prior to analysis on Earth may partially negate the scientific value of a sample return mission, particularly the desire to search for possible signs of living organisms or traces thereof in the samples. Full success of sample return missions from other celestial bodies therefore may depend upon the achievement and verification of sample containment. Additionally, sample containment is most problematic in the final phase of such missions, comprising entry of the sample return system into the upper atmosphere, its contact with Earth, and its final retrieval.
In addition to sample return missions from other celestial bodies, it may be desirable to rapidly and directly return experiments from space platforms in Earth orbit, such as the International Space Station, rather than wait for available return cargo space in a manned space vehicle (e.g., the Space Shuttle). Such rapid experiment return missions present many of the same requirements as sample return missions from other celestial bodies.
Some previously planned sample return missions have relied upon parachutes to slow the sample return capsule and thereby lower velocities prior to impact or aerocapture. However, due to the finite probability of parachute failure, success of sample containment for missions such as the MSR mission or rapid experiment return missions cannot rely on the proper deployment of decelerating parachutes. Therefore, sample return capsule designs incorporating a parachute may not be appropriate for the MSR mission and other missions.
Without decelerating parachutes for slowing capsule descent, high Earth impact velocities result, causing extremely high loading conditions upon impact of the capsule with the Earth""s surface. Also, high aerothermal heating and significant aerodynamic loads are present in the upper atmosphere. While some prior designs for thermal protection and structural support of reentry vehicles exist, prior reentry vehicles have not provided a relatively lightweight, aerodynamically stable, impact mitigating integrated solution to the direct and safe return of samples from space without the use of decelerating parachutes.
Accordingly, a need exists for an integrated sample return capsule capable of directly and safely returning samples from space to Earth without relying on decelerating parachutes. The present invention discloses an integrated sample return capsule that incorporates thermal protection, structural integrity and impact mitigation into a single system capable of safely returning samples from space without requiring the use of decelerating parachutes.
According to one aspect of the present invention there is provided an integrated sample return capsule for use in returning materials disposed within a sealable sample containment vault to Earth from space. The integrated sample return capsule includes a forward facing heat shield and a back shell that is attached to the rear of the heat shield. Together, the back shell and the heat shield define an interior enclosure. The back shell includes an access (e.g., a door or a removable panel) there through to the interior enclosure. Once the materials to be returned are sealed in the sample containment vault, the sealed vault may be placed into the interior enclosure through the access. In one embodiment, an optional support deck is mounted within the interior enclosure. The optional support deck is adapted to receive the sample containment vault and support the vault within the interior enclosure.
The heat shield, back shell, and optional support deck are configured to provide an aerodynamically stable capsule that provides thermal protection, structural integrity and impact mitigation. In this regard, the forward facing heat shield may include a blunt forward nose portion and extend outwardly in a conical fashion therefrom to an aft rim. The heat shield may be comprised of an outer shell including an ablative first material (e.g., a rigid ablative material such as carbon/carbon, carbon/phenolic, carbon matrix composite, and ceramic matrix composite, or a nonrigid ablative material such as phenolic impregnated carbon ablator) and an inner insulating and crushable layer including an insulating and crushable second material (e.g., reticulated vitreous carbon foam, fibrous carbon insulation, non-fibrous graphite foam, ceramic foam, carbon felt, ceramic felt, and carbon aerogel). The back shell may, for example, comprise an ablative outer material (e.g., super lightweight ablator) over an underlying structure (e.g., an aluminum honeycomb sandwich panel or a composite structure), and may include a flat back portion (in which the access may be provided) and a conical annulus terminating in a fore rim in contact with the aft rim of the heat shield. The back shell may be attached to the heat shield by a plurality of brackets disposed within the interior enclosure and fastened to interior surfaces of the heat shield and back shell at various locations adjacent to their respective aft and fore rims. The optional support deck preferably supports the sample containment vault in a spaced relation with the inner layer and in a substantially centered position behind the blunt forward nose portion. The relatively thin heat shield permits the sample containment vault to be supported in a forward position by the support deck, thereby providing the capsule with a forward center of gravity and, thus, satisfactory aerodynamic stability.
During reentry, the heat shield provides thermal protection for samples within the sample containment vault through ablation of the outer shell and the insulating nature of the inner insulating and crushable layer. Upon Earth impact, damage to the sealed sample containment vault is reduced or eliminated through destructive cracking of the outer shell of the heat shield and crushing of the inner insulating and crushable layer. In order to provide additional thermal and impact protection, there may be a second layer of insulating and crushable material within the interior enclosure between the support deck/sample containment vault and the heat shield.
According to another aspect of the present invention there is provided an integrated sample return capsule for use in returning materials to Earth from space. The integrated sample return capsule includes a forward facing outer face sheet comprised of an ablative first material (e.g., a rigid ablative material such as carbon/carbon, carbon/phenolic, carbon matrix composite, and ceramic matrix composite, or a non-rigid ablative material such as phenolic impregnated carbon ablator). A back shell (e.g., super lightweight ablator over an aluminum honeycomb sandwich panel or a composite structure) is attached to the outer face sheet rearward thereof, and together the back shell and the outer face sheet define an interior enclosure there between. A first layer of an insulating and crushable second material (e.g., reticulated vitreous carbon foam, fibrous carbon insulation, non-fibrous graphite foam, ceramic foam, carbon felt, ceramic felt, and carbon aerogel) within the interior enclosure backs at least a forward portion of the outer face sheet, and a second layer of an insulating and crushable third material (e.g., reticulated vitreous carbon foam, fibrous carbon insulation, non-fibrous graphite foam, ceramic foam, carbon felt, ceramic felt, and carbon aerogel) within the interior enclosure backs at least the first layer. A sealable sample containment vault is disposed within the interior enclosure and is supported by at least one of the first and second layers of insulating and crushable material. The sample containment vault may be spherically shaped and there may be a corresponding hemispherical cut-out in one or both of the first and second layers into which the forward portion of the sample containment vault is fit. The back shell may include an access (e.g., a door or a removable panel) there through to the interior enclosure thereby allowing placement of materials into the sample containment vault and sealing of the vault prior to reentry (and removal of the vault after impact). Alternatively, materials being returned may be sealed in the sample containment vault and the vault positioned in the interior enclosure prior to attachment of the back shell.
According to one more aspect of the present invention, there is provided an integrated sample return capsule for use in returning materials to Earth from space that includes a forward facing heat shield and a back shell attached to the rear of the heat shield. The back shell and the heat shield define an interior enclosure there between. There may be an optional support deck mounted within the interior enclosure and a sealable sample containment vault may disposed within the interior enclosure and supported therein on the support deck. Materials to be returned may be placed within the sample containment vault through an access (e.g., a door or a removable panel) in the back shell to the interior enclosure and the vault may then be sealed prior to reentry. Alternatively, if no access is provided to the interior enclosure, materials being returned may be sealed in the sample containment vault and the vault positioned on the support deck prior to attachment of the back shell.
These and other aspects and advantages of the present invention will be readily apparent to one skilled in the art from the following figures, descriptions, and claims.